In the rapidly advancing world of semiconductor device technology, integrated circuit and other semiconductor devices are being formed with increased complexities and with features that include increasingly smaller dimensions. Even though such semiconductor devices are being formed to increased integration levels and increased complexity levels, the drive to increase device speed continues in a most aggressive manner.
In addition to being determined by device design, i.e. the layout of the device, device speed is heavily dependent upon the nature and composition of the conductive materials used in the manufacture of the device and also the contacts between the different conductive features of the device. As device complexities continue to increase and as advanced new conductive materials continue to be developed, various types of contacts are utilized and it is desirable to minimize the contact resistance associated with each of the contacts. Contacts are formed at various levels in the semiconductor device and between various conductive features that are disposed at various levels of the device. Furthermore, in order to fabricate semiconductor devices most efficiently and using an economy of processing operations, it is useful to form various different types of contacts using the same processing operations. For example, contacts through different kinds of material may be simultaneously formed using the same sequence of processing operations.
It is advantageous to form multiple different contacts extending through a dielectric layer or layers, simultaneously, even if the subjacent materials to which contact is made, are different materials. One example is in CMOS, complementary metal oxide semiconductor technology, for example in CIS (CMOS image sensors), and flash memory devices in which it may be desirable to form contacts to different materials through the same dielectric layer or layers simultaneously, using the same sequence of processing operations.
When contacts extend through a particular dielectric layer or layers to different subjacent materials, the electrical requirements of the different contacts make it difficult to form the contacts using the same set of processing operations. For example, the sequence of processing operations that may advantageously be used to form a contact structure that contacts a silicide surface, may utilize processing conditions and characteristics that render the contact structure incapable of satisfying the electrical requirements of other contacts.
Structures and methods that address the above shortcomings and limitations are needed.